Fireproofing compound and method of making same.



I UNITED STATES PATENT OFFICE.

JOSEPH L. FERRELL, OF PHILADELPHIA, PENNSYLVANIA.

FIREPROOFING COMPOUND AND METHOD OF MAKING SAME.

SPECIFICATION forming part of Letters Patent N 0. 695,679, dated March 18, 1902.

Application filerl April 29, 1901. Serial No. 58,099. (No specimens.)

To all whom it may concern.-

Be it known that I, JOSEPH L. FERRELL, of Philadelphia, in the State of Pennsylvania, have invented certain new and useful Improvements in Fireproofing Compounds and in the Art of Making the Same, whereof the following is aspecification.

It is the object of my invention to provide a liquid compound which when applied to cellular substances of a normally inflammable nature shall suffice to render such substance incapable of supporting combustion.

My compound is particularly applicable to wood, and I will simplify the following description by adverting only to that substance, it being understood, however, that I do not, therefore, intend to limit myself to such use.

I have ascertained that wood is rendered fireproof if impregnated with an aqueous solution of aluminium sulfate perse, and I have found it advantageous to .employ such a solution having a density indicated by 25 Baum. Although treatment with a solution of commercial aluminium sulfate per se suffices to render Wood fireproof, I find that wood treated with such a solution is more or less stained and discolored. Of course the aforesaid characteristic results prohibit the use of said solution in the treatment of woods which are to be naturally finished, although of no importance in the treatment of woods which are not to be thus finished. However, I have discovered that such staining of the wood may be absolutely prevented if a basic chemical is added to the solution of aluminium sulfate. For instance, the addition of a small percentage of magnesium carbonate or ammonium carbonate or both magnesium carbonate and ammonium carbonate to the solution suffices to prevent such staining and the product is of the natural color of the wood. Moreover, I find that if wood treated with the solution of aluminium sulfate per se is subjected to an extremely high temperature, such as is obtainable with a Bunsen blast-burner, and, of course, higher than any temperature to which the wood would be subjected under normal conditions of exposure to flame, a minute quantity of combustible gas may be gen: erated from the wood thus treated, which is manifested in a lingering flicker of flame if the wood tested is quickly removed from exposure to theblast. The addition of a basic chemical to the solution of aluminium sulfate, as aforesaid, is of additional advantage in that the last-named phenomenon is thereby prevented. I.

The chemicals specified of the ordinary commercial grade which I have employed vary largely in their characteristics. For instance, the contents of one bag or barrel differ from another of the same shipmeut,so that although approximately three pounds of commercial sulfate of aluminium is required to produce one gallon of a solution having a density inindicated by 25 Baum I have found that insome cases less than three pounds and in other cases nearly five pounds are required for such result. SimilarlyI have found the capacity of the aluminium sulfate solution to stain or discolor the product and to produce the flame linger aforesaid may be'eliminated in some instances by the addition of one or two ounces of the basicchemical to each gallon of the solution, while in other instances more than six ounces is required to each gallon of the solution to effect the desired result. Therefore I have found it.necessary to determine by testing each lot of the chemicals whichI have employed, first, the quantity per volume of solution necessary to produce any desired degree of density of the latter, and, second, the amount of basic chemical required to be added to secure the result specified.

In view of the aforesaid variable nature of the chemicals employed I do not desire to limit myself eitheras to the density of my liquid compound or to the specified proportions of its ingredients. However, it is to be noted that only such a percentage of basic chemical should be used in association with the aluminium sulfate as shall not be quite sufficient .to completely neutralize the acidityof the solution, for the reason that complete neutralization is accompanied by precipitation of the salt formed, which of course interferes with the manipulation of the solution in any apparatus in which it is employed. Moreover, although the carbonates named may be advantageously employed on account of their low cost, it is to be understood that any basic chemical may be utilized in association with aluminium sulfate in my liquid compound which will not make an insoluble pt't. c.ipitate therein.

In viewof the fact thatthere is usually free acid in commercial aluminium sulfate the introduction of magnesium carbonate to the solution of the aluminium sulfate, as above (lescribed, of eon rse suffices to form magnesium sulfate in said solution, and, similarly, the addition of anunenium carbonate to the solution of aluminium sulfate sufliees to form ammonium sulfate therein. Therefore 1 have specified the last-named sulfates in certain of the following claims.

I claim- 1. The hereinbefore-described tireprooling compound, consisting of an aqueous solution of aluminium sulfate mixed with another chemical capable of obviating the discoloriug effect of the aluminium sulfate per se, substantially as set forth.

2. The hereinbefore-deseribod tireproofing compound, consisting of an aqueous solution of aluminium sulfate mixed with the residue of a carbonate decomposed in the presence of said sulfate, substantially as set forth.

:3. The hereinbefore-described process of making a lireprooling compound, which consists in making anaqueous solution of aluminium sulfate, and mixing with said solution anotherehemieal capable of obviating, the diseoloriug effect of the aluminium sulfate per s0, substantially as set forth.

-t. The hereinbefore-described process of making a fireprooting, compound, which consists in making an aqueous solution of aluminium sulfate, and mixing with said solution a carbonate, substantially as set forth.

In testimony whereof I have hereunto signed my name, at Philadelphia, Pennsylvania, this 26th day of April, 1901.

JOSEPH L. FERRELL.

\Vitnesses:

An'rnun E. Paton, tluonun I. Sutton). 

